GNAS and polyostotic fibrous dysplasia: In 1991, Weinstein et al. (21) described Gsα subunit (GNAS) mutations in individuals with McCune-Albright syndrome (MAS); MAS is classically associated with polyostotic fibrous dysplasia, café-au-lait skin spots, and precocious puberty but also with adrenal hyperplasia and/or tumors (21).